diff --git a/src/__tests__/api.interceptor.spec.ts b/src/__tests__/api.interceptor.spec.ts
new file mode 100644
index 00000000..7fbb3ad7
--- /dev/null
+++ b/src/__tests__/api.interceptor.spec.ts
@@ -0,0 +1,21 @@
+/// <reference types="jest" />
+import { addSignatureFn } from '../lib/api/helper/interceptors';
+
+const packageJSON = require('../../package.json');
+
+describe('API request interceptor', () => {
+    it('adds fdk cli version header before service requests are signed', async () => {
+        const interceptor = addSignatureFn({});
+        const config: any = {
+            url: 'https://api.fyndx1.de/service/panel/authentication/v1.0/oauth/token',
+            method: 'get',
+            headers: {},
+        };
+
+        const signedConfig = await interceptor(config);
+
+        expect(signedConfig.headers['x-fp-cli']).toBe(`${packageJSON.version}`);
+        expect(signedConfig.headers['x-fp-date']).toBeDefined();
+        expect(signedConfig.headers['x-fp-signature']).toBeDefined();
+    });
+});
diff --git a/src/__tests__/auth.device.spec.ts b/src/__tests__/auth.device.spec.ts
new file mode 100644
index 00000000..7dc1c722
--- /dev/null
+++ b/src/__tests__/auth.device.spec.ts
@@ -0,0 +1,165 @@
+/// <reference types="jest" />
+import rimraf from 'rimraf';
+import Auth from '../lib/Auth';
+import ApiClient from '../lib/api/ApiClient';
+import Env from '../lib/Env';
+import configStore, { CONFIG_KEYS } from '../lib/Config';
+import OrganizationService from '../lib/api/services/organization.service';
+import CommandError from '../lib/CommandError';
+import Logger from '../lib/Logger';
+
+const openMock = jest.fn();
+
+jest.mock('open', () => ({
+    __esModule: true,
+    default: (...args) => openMock(...args),
+}));
+
+jest.mock('../helper/formatter', () => ({
+    OutputFormatter: {
+        link: (value: string) => value,
+        command: (value: string) => value,
+    },
+    successBox: ({ text }: { text: string }) => text,
+}));
+
+jest.mock('configstore', () => {
+    const Store = jest.requireActual('configstore');
+    return class MockConfigstore {
+        store = new Store('test-cli', undefined, {
+            configPath: './auth-device-test-cli.json',
+        });
+        get(key: string) {
+            return this.store.get(key);
+        }
+        set(key: string, value) {
+            this.store.set(key, value);
+        }
+        delete(key) {
+            this.store.delete(key);
+        }
+        clear() {
+            this.store.clear();
+        }
+    };
+});
+
+describe('Auth device flow', () => {
+    beforeEach(() => {
+        jest.restoreAllMocks();
+        jest.clearAllMocks();
+        configStore.clear();
+        process.exitCode = 0;
+
+        jest.spyOn(Env, 'verifyAndSanitizeEnvValue').mockResolvedValue('api.fyndx1.de');
+        jest.spyOn(Env, 'getEnvValue').mockReturnValue('api.fyndx1.de');
+        jest.spyOn(Logger, 'info').mockImplementation(() => {});
+        jest.spyOn(OrganizationService, 'getOrganizationDetails').mockResolvedValue({
+            data: { _id: 'org-1', name: 'Test Org' },
+        } as any);
+        openMock.mockResolvedValue(undefined);
+    });
+
+    afterEach(() => {
+        process.exitCode = 0;
+    });
+
+    afterAll(() => {
+        rimraf.sync('./auth-device-test-cli.json');
+    });
+
+    it('falls back to legacy when client-config endpoint is unavailable', async () => {
+        jest.spyOn(ApiClient, 'get').mockRejectedValue({
+            response: { status: 404 },
+        });
+
+        await expect((Auth as any).getAuthFlowConfig('api.fyndx1.de')).resolves.toEqual({
+            auth_mode: 'legacy',
+        });
+    });
+
+    it('does not fall back to legacy when client-config returns an unexpected error', async () => {
+        const error = {
+            message: 'Internal server error',
+            response: { status: 500 },
+        };
+        jest.spyOn(ApiClient, 'get').mockRejectedValue(error);
+
+        await expect((Auth as any).getAuthFlowConfig('api.fyndx1.de')).rejects.toBe(error);
+    });
+
+    it('uses device flow and appends missing URL params', async () => {
+        const getSpy = jest.spyOn(ApiClient, 'get').mockResolvedValue({
+            data: {
+                client_id: 'fdk-cli',
+                auth_mode: 'device_code',
+            },
+        } as any);
+
+        const postSpy = jest.spyOn(ApiClient, 'post');
+        postSpy
+            .mockResolvedValueOnce({
+                data: {
+                    device_code: 'device-code-1',
+                    user_code: 'ABCD-EFGH',
+                    verification_uri_complete: 'https://partners.fyndx1.de/activate-with-code',
+                    interval: 0,
+                    expires_in: 10,
+                },
+            } as any)
+            .mockResolvedValueOnce({
+                data: {
+                    auth_token: {
+                        access_token: 'token-1',
+                        expires_in: 3600,
+                        current_user: { first_name: 'A', last_name: 'B', emails: [] },
+                    },
+                    organization: { _id: 'org-1', name: 'Test Org' },
+                },
+            } as any);
+
+        await Auth.login({ host: 'api.fyndx1.de' });
+
+        expect(getSpy).toHaveBeenCalled();
+        expect(postSpy).toHaveBeenCalledTimes(2);
+        expect(openMock).toHaveBeenCalledTimes(1);
+        const openedUrl = openMock.mock.calls[0][0] as string;
+        expect(openedUrl).toContain('user_code=ABCD-EFGH');
+        expect(openedUrl).toContain('device_flow=true');
+        expect(configStore.get(CONFIG_KEYS.AUTH_TOKEN).access_token).toBe('token-1');
+    });
+
+    it('maps expired_token polling response to CommandError', async () => {
+        jest.spyOn(ApiClient, 'get').mockResolvedValue({
+            data: {
+                client_id: 'fdk-cli',
+                auth_mode: 'device_code',
+            },
+        } as any);
+
+        const postSpy = jest.spyOn(ApiClient, 'post');
+        postSpy
+            .mockResolvedValueOnce({
+                data: {
+                    device_code: 'device-code-2',
+                    user_code: 'WXYZ-2345',
+                    verification_uri_complete:
+                        'https://partners.fyndx1.de/activate-with-code?user_code=WXYZ-2345&device_flow=true',
+                    interval: 0,
+                    expires_in: 10,
+                },
+            } as any)
+            .mockRejectedValueOnce({
+                response: { data: { error: 'expired_token' } },
+            });
+
+        try {
+            await Auth.login({ host: 'api.fyndx1.de' });
+            fail('Expected Auth.login to throw for expired_token');
+        } catch (error) {
+            expect(error).toBeInstanceOf(CommandError);
+            expect(error.message).toBe('Device code expired. Please run `fdk login` again.');
+            expect(error.code).toBe('400');
+        }
+    });
+});
diff --git a/src/__tests__/url.spec.ts b/src/__tests__/url.spec.ts
new file mode 100644
index 00000000..16187e9a
--- /dev/null
+++ b/src/__tests__/url.spec.ts
@@ -0,0 +1,42 @@
+jest.mock('../lib/Config', () => {
+    const actual = jest.requireActual<typeof import('../lib/Config')>(
+        '../lib/Config',
+    );
+    const { CONFIG_KEYS } = actual;
+    return {
+        __esModule: true,
+        default: {
+            get: (key: string) => {
+                if (key === CONFIG_KEYS.API_VERSION) return '1.0';
+                if (key === CONFIG_KEYS.CURRENT_ENV_VALUE) {
+                    return 'api.test.example.com';
+                }
+                return undefined;
+            },
+        },
+        CONFIG_KEYS: actual.CONFIG_KEYS,
+    };
+});
+
+import { URLS } from '../lib/api/services/url';
+
+describe('URLS OAuth (device flow)', () => {
+    const authBase =
+        'https://api.test.example.com/service/panel/authentication/v1.0';
+
+    it('OAUTH_CLIENT_CONFIG builds panel client-config URL', () => {
+        expect(URLS.OAUTH_CLIENT_CONFIG()).toBe(
+            `${authBase}/oauth/client-config`,
+        );
+    });
+
+    it('OAUTH_DEVICE_AUTHORIZATION builds device authorization URL', () => {
+        expect(URLS.OAUTH_DEVICE_AUTHORIZATION()).toBe(
+            `${authBase}/oauth/device_authorization`,
+        );
+    });
+
+    it('OAUTH_DEVICE_TOKEN builds OAuth token URL', () => {
+        expect(URLS.OAUTH_DEVICE_TOKEN()).toBe(`${authBase}/oauth/token`);
+    });
+});
diff --git a/src/lib/Auth.ts b/src/lib/Auth.ts
index c7ddbba6..2139b199 100644
--- a/src/lib/Auth.ts
+++ b/src/lib/Auth.ts
@@ -18,6 +18,7 @@ import { OutputFormatter, successBox } from '../helper/formatter';
 import OrganizationService from './api/services/organization.service';
 import { getOrganizationDisplayName } from '../helper/utils';
 import ExtensionContext from './ExtensionContext';
+import ApiClient from './api/ApiClient';
 
 async function checkTokenExpired(auth_token) {
     const { expiry_time } = auth_token;
@@ -29,6 +30,8 @@ async function checkTokenExpired(auth_token) {
     }
 }
 
+const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
+
 export const getApp = async () => {
     const app = express();
     let isLoading = false;
@@ -145,6 +148,127 @@ export default class Auth {
     static wantToChangeOrganization = false;
     static newDomainToUpdate = null;
     constructor() { }
+
+    private static async getAuthFlowConfig(env: string) {
+        try {
+            const url = `https://${env}/service/panel/authentication/v1.0/oauth/client-config`;
+            const response = await ApiClient.get(url, {
+                params: { client_id: 'fdk-cli' },
+                headers: {
+                    'Content-Type': 'application/json',
+                },
+            });
+            return response.data || {};
+        } catch (error) {
+            if (error?.response?.status === 404) {
+                return { auth_mode: 'legacy' };
+            }
+            throw error;
+        }
+    }
+
+    private static shouldUseDeviceFlow(config: { auth_mode?: string }) {
+        return (config?.auth_mode || '').toLowerCase() === 'device_code';
+    }
+
+    private static async runDeviceLogin(env: string, options: any) {
+        const authBase = `https://${env}/service/panel/authentication/v1.0`;
+        const response = await ApiClient.post(`${authBase}/oauth/device_authorization`, {
+            headers: {
+                'Content-Type': 'application/json',
+            },
+            data: {
+                client_id: 'fdk-cli',
+                scope: ['organization/*'],
+                requested_host: env,
+                requested_region: options.region?.trim(),
+            },
+        });
+        const {
+            device_code,
+            user_code,
+            verification_uri_complete,
+            interval = 5,
+            expires_in = 600,
+        } = response.data;
+
+        const verificationUrl = new URL(verification_uri_complete);
+        if (!verificationUrl.searchParams.has('user_code')) {
+            verificationUrl.searchParams.set('user_code', user_code);
+        }
+        if (!verificationUrl.searchParams.has('device_flow')) {
+            verificationUrl.searchParams.set('device_flow', 'true');
+        }
+        const verificationLink = verificationUrl.toString();
+
+        Logger.info(`User verification code: ${chalk.cyan(user_code)}`);
+        try {
+            await open(verificationLink);
+            console.log(`Opened link to start the auth process: ${OutputFormatter.link(verificationLink)}`);
+        } catch (err) {
+            console.log(`Open this link to continue login: ${OutputFormatter.link(verificationLink)}`);
+        }
+
+        const maxAttempts = Math.ceil(expires_in / interval);
+        for (let attempt = 0; attempt < maxAttempts; attempt++) {
+            await sleep(interval * 1000);
+            try {
+                const tokenRes = await ApiClient.post(`${authBase}/oauth/token`, {
+                    headers: {
+                        'Content-Type': 'application/json',
+                    },
+                    data: {
+                        grant_type: 'urn:ietf:params:oauth:grant-type:device_code',
+                        client_id: 'fdk-cli',
+                        device_code,
+                    },
+                });
+                const authToken = tokenRes.data.auth_token;
+                const organization = tokenRes.data.organization;
+                if (Auth.wantToChangeOrganization) {
+                    ConfigStore.delete(CONFIG_KEYS.AUTH_TOKEN);
+                    clearExtensionContext();
+                }
+                const expiryTimestamp =
+                    Math.floor(Date.now() / 1000) + authToken.expires_in;
+                authToken.expiry_time = expiryTimestamp;
+                if (Auth.newDomainToUpdate) {
+                    if (Auth.newDomainToUpdate === 'api.fynd.com') {
+                        Env.setEnv(Auth.newDomainToUpdate);
+                    }
+                    else {
+                        await Env.setNewEnvs(Auth.newDomainToUpdate);
+                    }
+                }
+                ConfigStore.set(CONFIG_KEYS.AUTH_TOKEN, authToken);
+                ConfigStore.set(CONFIG_KEYS.ORGANIZATION, organization);
+                const organization_detail =
+                    await OrganizationService.getOrganizationDetails();
+                ConfigStore.set(
+                    CONFIG_KEYS.ORGANIZATION_DETAIL,
+                    organization_detail.data,
+                );
+                Logger.info(`Logged in successfully in organization ${getOrganizationDisplayName()}`);
+                return;
+            } catch (error) {
+                const oauthError = error?.response?.data?.error;
+                if (oauthError === 'authorization_pending') continue;
+                if (oauthError === 'slow_down') {
+                    await sleep(2000);
+                    continue;
+                }
+                if (oauthError === 'access_denied') {
+                    throw new CommandError('Login denied in browser.', '403');
+                }
+                if (oauthError === 'expired_token') {
+                    throw new CommandError('Device code expired. Please run `fdk login` again.', '400');
+                }
+                throw error;
+            }
+        }
+        throw new CommandError('Login timed out. Please run `fdk login` again.', '408');
+    }
+
     public static async login(options) {
 
         let env: string;
@@ -186,12 +310,19 @@ export default class Auth {
                     return;
                 } else {
                     Auth.wantToChangeOrganization = true;
-                    await startServer(port);
                 }
             });
-        } else
-            await startServer(port);
+            if (!Auth.wantToChangeOrganization) {
+                return;
+            }
+        }
         try {
+            const authFlowConfig = await Auth.getAuthFlowConfig(env);
+            if (Auth.shouldUseDeviceFlow(authFlowConfig)) {
+                await Auth.runDeviceLogin(env, options);
+                return;
+            }
+            await startServer(port);
             let domain = null;
             let partnerDomain = env.replace('api', 'partners');
             domain = `https://${partnerDomain}`;
diff --git a/src/lib/api/helper/interceptors.ts b/src/lib/api/helper/interceptors.ts
index d248159c..c3e86ad0 100644
--- a/src/lib/api/helper/interceptors.ts
+++ b/src/lib/api/helper/interceptors.ts
@@ -10,6 +10,8 @@ import { transformRequestOptions } from '../../../helper/utils';
 import fs from 'fs-extra';
 import https from 'https'
 
+const packageJSON = require('../../../../package.json');
+
 function getTransformer(config) {
     const { transformRequest } = config;
 
@@ -40,6 +42,8 @@ function interceptorFn(options) {
             }
             const { host, pathname, search } = new URL(url);
             if (pathname.includes('/service') || pathname.startsWith('/ext')) {
+                config.headers = config.headers || {};
+                config.headers['x-fp-cli'] = config.headers['x-fp-cli'] || `${packageJSON.version}`;
                 const { data, headers, method, params } = config;
                 // set cookie
                 const cookie = ConfigStore.get(CONFIG_KEYS.COOKIE);
diff --git a/src/lib/api/services/url.ts b/src/lib/api/services/url.ts
index 61888fd4..e25cc8e6 100644
--- a/src/lib/api/services/url.ts
+++ b/src/lib/api/services/url.ts
@@ -43,6 +43,15 @@ export const URLS = {
     VERIFY_OTP: () => {
         return urlJoin(AUTH_URL(), '/auth/login/mobile/otp/verify');
     },
+    OAUTH_CLIENT_CONFIG: () => {
+        return urlJoin(AUTH_URL(), '/oauth/client-config');
+    },
+    OAUTH_DEVICE_AUTHORIZATION: () => {
+        return urlJoin(AUTH_URL(), '/oauth/device_authorization');
+    },
+    OAUTH_DEVICE_TOKEN: () => {
+        return urlJoin(AUTH_URL(), '/oauth/token');
+    },
 
     //CONFIGURATION
     GET_APPLICATION_DETAILS: (company_id: number, application_id: string) => {